Frustration

Google evidently has two separate account namespaces:

Google Accounts

Google Apps account

Google Accounts can be, but are not?necessarily, a Google Mail/Gmail account. One can have a Google Account without having a Gmail account (e.g. user@example.com) and can use such an account for accessing services like Google Reader, Google Docs, etc. I created such an account years ago for my personal email address.
Google Apps accounts are accounts associated with Google Apps, which are separate from regular Google Accounts. Google Apps provides email service for my personal domain.
Unfortunately, this means that both my Google Account and Google Apps account had the same username, which lead to considerable confusion.
I’m just now trying to get this all straightened out by only using Google Apps for email and XMPP chat and migrating all my other services (like Google Reader, Google Voice, etc.) to a single Google Account. This is exceedingly frustrating.